1. Field of the Invention
The present invention relates to novel synthetic zeolitic fillers having a high degree of dispersibility, and, more especially, to the use of such zeolites as reinforcing fillers for polymeric matrices.
2. Description of the Prior Art
It has long been known to utilize mineral fillers to improve or enhance certain properties of elastomeric polymer matrices in particular, and the plastics in general.
Unfortunately, the incorporation of, and reinforcement with, such fillers may suffer from two types of disadvantage, one being an economic disadvantage, if the cost of the filler is excessively high, and the other being a technical disadvantage, if the improvement made in the properties by reason of the filler is at the expense of other properties, which is often the case.
In addition, the behavior of the filler is also often characteristic of the filler/elastomer or filler/plastic pair, for reasons which are related to the morphology of the filler, and the polymer matrix, and surface chemistry. Thus, certain generally accepted laws have been more or less properly verified. However, with the conventional fillers, in certain instances it has been found that a coarser filler displays better dispersion than a finer filler.
Accordingly, considerable studies were conducted by the present applicants as to those factors likely to result in good dispersion, and in an effort to provide a filler which satisfies the requirement of good dispersibility; also to verify the benefit thereof in regard to improving certain behaviour in specific cases, albeit it will of course be appreciated that such specific instances are not to be construed as in any way limiting the present invention.
In particular, applicants' such efforts have been oriented as regards the zeolites. Indeed, it is known that the natural zeolites have already been incorporated in polypropylene; see Natural Zeolites by L. B. Sand and F. A. Mumpton, Pergamon Press, page 447. The results set forth in the noted publication reveal, for example, that polypropylene reinforced with a clinoptilolite filler suffers from a reduction in its impact strength.
It has also been proposed that the impact or shock properties of polypropylene might be improved with calcium carbonate-based fillers. However, any improvement achieved in regard to shock properties is quite often insufficient in relation to the requirements necessary for the particular uses intended.